On Tue, 20 Jun 2023 at 14:44, Christian Loehle <CLoehle@xxxxxxxxxxxxxx> wrote:
>
> Userspace currently has no way of checking for error bits of
> detection mode X. These are error bits that are only detected by
> the card when executing the command. For e.g. a sanitize operation
> this may be minutes after the RSP was seen by the host.
>
> Currently userspace programs cannot see these error bits reliably.
> They could issue a multi ioctl cmd with a CMD13 immediately following
> it, but since errors of detection mode X are automatically cleared
> (they are all clear condition B).
> mmc_poll_for_busy of the first ioctl may have already hidden such an
> error flag.
>
> In case of the security operations: sanitize, secure erases and
> RPMB writes, this could lead to the operation not being performed
> successfully by the card with the user not knowing.
> If the user trusts that this operation is completed
> (e.g. their data is sanitized), this could be a security issue.
> An attacker could e.g. provoke a eMMC (VCC) flash fail, where a
> successful sanitize of a card is not possible. A card may move out
> of PROG state but issue a bit 19 R1 error.
>
> This patch therefore will also have the consequence of a mmc-utils
> patch, which enables the bit for the security-sensitive operations.
>
> Signed-off-by: Christian Loehle <cloehle@xxxxxxxxxxxxxx>
> ---
> drivers/mmc/core/block.c | 26 +++++++++++++++-----------
> drivers/mmc/core/mmc_ops.c | 14 +++++++-------
> drivers/mmc/core/mmc_ops.h | 9 +++++++++
> 3 files changed, 31 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index e46330815484..c7e2b8ae58a9 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -470,7 +470,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
> struct mmc_data data = {};
> struct mmc_request mrq = {};
> struct scatterlist sg;
> - bool r1b_resp, use_r1b_resp = false;
> + bool r1b_resp;
> unsigned int busy_timeout_ms;
> int err;
> unsigned int target_part;
> @@ -551,8 +551,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
> busy_timeout_ms = idata->ic.cmd_timeout_ms ? : MMC_BLK_TIMEOUT_MS;
> r1b_resp = (cmd.flags & MMC_RSP_R1B) == MMC_RSP_R1B;
> if (r1b_resp)
> - use_r1b_resp = mmc_prepare_busy_cmd(card->host, &cmd,
> - busy_timeout_ms);
> + mmc_prepare_busy_cmd(card->host, &cmd, busy_timeout_ms);
>
> mmc_wait_for_req(card->host, &mrq);
> memcpy(&idata->ic.response, cmd.resp, sizeof(cmd.resp));
> @@ -605,19 +604,24 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
> if (idata->ic.postsleep_min_us)
> usleep_range(idata->ic.postsleep_min_us, idata->ic.postsleep_max_us);
>
> - /* No need to poll when using HW busy detection. */
> - if ((card->host->caps & MMC_CAP_WAIT_WHILE_BUSY) && use_r1b_resp)
> - return 0;
> -
> if (mmc_host_is_spi(card->host)) {
> if (idata->ic.write_flag || r1b_resp || cmd.flags & MMC_RSP_SPI_BUSY)
> return mmc_spi_err_check(card);
> return err;
> }
> - /* Ensure RPMB/R1B command has completed by polling with CMD13. */
> - if (idata->rpmb || r1b_resp)
> - err = mmc_poll_for_busy(card, busy_timeout_ms, false,
> - MMC_BUSY_IO);
> + /* Poll for RPMB/write/R1B execution errors */
Except for the other comments that I had on v2 (which isn't addressed
in v3), I would like this comment to be extended a bit.
More precisely, we somehow need to state that even if the host
supports HW busy signaling (MMC_CAP_WAIT_WHILE_BUSY) we need to send a
CMD13 to get the internal error status of the card.
> + if (idata->rpmb || idata->ic.write_flag || r1b_resp) {
> + struct mmc_busy_data cb_data;
> +
> + cb_data.card = card;
> + cb_data.retry_crc_err = false;
> + cb_data.aggregate_err_flags = true;
> + cb_data.busy_cmd = MMC_BUSY_IO;
> + cb_data.status = &idata->ic.response[0];
> + err = __mmc_poll_for_busy(card->host, 0, busy_timeout_ms,
> + &mmc_busy_cb, &cb_data);
> +
> + }
>
> return err;
> }
[...]
Kind regards
Uffe
